Sequential numbering

this is just one way to do it - other will advise you of other methods

in the trigger on create of the subtable myJobs) assuming your subtable (child) is MyJobs

and the number field wher to numbering is to increment is called something like “Job Bag No”

enter this script

let before := max((select MyJobs).“Job Bag No”);
“Job Bag No” := before + 1

“Job bags No” needs to be a number field

Then when you creare a NEW entry it will auto number

after the plus + you can put any value in steps ie  2 or 6 etc

Note: if it does not appear to work add the first number manually into the first record ie 0 or 1 

Mel

heres mine in one of my forms

and here is the result

dunno why the screen shots not loaded - never ever done that before but you get the idea from the script

Nope def broken !!!

Something similar has been discussed here:

https://ninox.com/en/forum/technical-help-5ab8fe445fe2b42b7dd39ee7/illusion-of-inserting-new-lines-into-middle-of-child-table-invoiceorderquote-lines-5f942755415f765724960376?post=5f982a309b9a930f442143da&page=1